将监听器添加到ActionBar项目，onOptionsItemSelected空指针异常

Question

* 已回答！：*事实证明，即使您有一个项目的图标，也需要标题。

我目前在我的应用程序中实施（Sherlock）Action Bar。我目前有一个屏幕上的按钮，刷新我的屏幕视图，我想将此按钮移动到我的操作栏中。 onOptionsItemSelected的日志没有显示在LogCat中，但创建的菜单正在显示。

我不知道为什么我得到一个空指针，并且在错误日志中找不到发生null的地方。当我点击操作栏中的刷新按钮时，该应用程序只会崩溃，并且一切正常，直到该点。

public boolean onCreateOptionsMenu(Menu menu) { 
     Log.i("Created Menu", "Yes"); 
     MenuInflater inflater = getSupportMenuInflater(); 
     inflater.inflate(R.menu.main, menu); 


     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item){ 
     Log.i("Got into onOptionsItemSelected", "Yes"); 
     switch(item.getItemId()){ 

     case R.id.action_refresh: 

       new getFleetList().execute(getFleetListURL); 
       progressBar.setVisibility(ProgressBar.VISIBLE); 

     return true; 

    } 

---

堆栈跟踪：

07-09 12:52:27.594: W/dalvikvm(23570): threadid=1: thread exiting with uncaught exception (group=0x4132e930) 
07-09 12:52:27.601: E/AndroidRuntime(23570): FATAL EXCEPTION: main 
07-09 12:52:27.601: E/AndroidRuntime(23570): java.lang.NullPointerException 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.view.menu.MenuItemImpl.toString(MenuItemImpl.java:496) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at java.lang.StringBuilder.append(StringBuilder.java:202) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.actionbarsherlock.app.SherlockFragmentActivity.onMenuItemSelected(SherlockFragmentActivity.java:201) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:980) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:547) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:115) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at android.view.View.performClick(View.java:4204) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at android.view.View$PerformClick.run(View.java:17355) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at android.os.Handler.handleCallback(Handler.java:725) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at android.os.Handler.dispatchMessage(Handler.java:92) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at android.os.Looper.loop(Looper.java:137) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at android.app.ActivityThread.main(ActivityThread.java:5041) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at java.lang.reflect.Method.invokeNative(Native Method) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at java.lang.reflect.Method.invoke(Method.java:511) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 
07-09 12:52:27.601: E/AndroidRuntime(23570): at dalvik.system.NativeStart.main(Native Method) 

编辑，XML文件：

菜单XML：

<menu xmlns:android="http://schemas.android.com/apk/res/android" > 




    <item 
     android:id="@+id/action_refresh" 
     android:icon="@drawable/ic_action_refresh" 
     android:orderInCategory="1" 
     android:showAsAction="always" 

     /> 


</menu> 

Answer 1

您使用的这些进口

import com.actionbarsherlock.view.Menu; 
import com.actionbarsherlock.view.MenuItem; 

否则您会收到错误消息。

试试这个

@Override 
public boolean onCreateOptionsMenu(com.actionbarsherlock.view.Menu menu) { 

    com.actionbarsherlock.view.MenuInflater inflate = getSupportMenuInflater(); 
    inflate.inflate(R.menu.main, menu); 

    return super.onCreateOptionsMenu(menu); 
} 


@Override 
public boolean onOptionsItemSelected(com.actionbarsherlock.view.MenuItem item) { 
    // Handle item selection 
    switch (item.getItemId()) { 
     case R.id.action_refresh: 
      //do whatever you want 
     break; 
     default: 
      return super.onOptionsItemSelected(item); 
    } 
} 

**** ****更新

<item 
     android:id="@+id/action_legalnotice" 
     android:orderInCategory="100" 
     android:title="Legal Notices"/> 
    <item 
     android:id="@+id/action_refresh" 
     android:icon="@drawable/ic_action_refresh" 
     android:orderInCategory="1" 
     android:showAsAction="always" 


android:title="Your title here please" 

     /> 

看到此链接了解详细信息：Null pointer exception showing in action bar sherlock library